From 1e548a84d69dcfba28ca705f2eb9889d0789836b Mon Sep 17 00:00:00 2001
From: Stephan Unverwerth <s.unverwerth@serenityos.org>
Date: Sat, 17 Sep 2022 17:50:43 +0200
Subject: [PATCH] LibSoftGPU: Define a simple shader instruction set

This adds a simple instruction set with basic operations and adds an
instruction list to the shader class.
---
 Userland/Libraries/LibSoftGPU/Device.cpp |  2 +-
 Userland/Libraries/LibSoftGPU/ISA.h      | 63 ++++++++++++++++++++++++
 Userland/Libraries/LibSoftGPU/Shader.cpp |  3 +-
 Userland/Libraries/LibSoftGPU/Shader.h   |  9 +++-
 4 files changed, 74 insertions(+), 3 deletions(-)
 create mode 100644 Userland/Libraries/LibSoftGPU/ISA.h

diff --git a/Userland/Libraries/LibSoftGPU/Device.cpp b/Userland/Libraries/LibSoftGPU/Device.cpp
index e971ad01a71..356b078bbe4 100644
--- a/Userland/Libraries/LibSoftGPU/Device.cpp
+++ b/Userland/Libraries/LibSoftGPU/Device.cpp
@@ -1638,7 +1638,7 @@ NonnullRefPtr<GPU::Image> Device::create_image(GPU::PixelFormat const& pixel_for
 
 ErrorOr<NonnullRefPtr<GPU::Shader>> Device::create_shader(GPU::IR::Shader const&)
 {
-    return adopt_ref(*new Shader(this));
+    return adopt_ref(*new Shader(this, {}));
 }
 
 void Device::set_sampler_config(unsigned sampler, GPU::SamplerConfig const& config)
diff --git a/Userland/Libraries/LibSoftGPU/ISA.h b/Userland/Libraries/LibSoftGPU/ISA.h
new file mode 100644
index 00000000000..4f34cfae1d8
--- /dev/null
+++ b/Userland/Libraries/LibSoftGPU/ISA.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2022, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace SoftGPU {
+
+constexpr u8 swizzle_pattern(u8 a, u8 b, u8 c, u8 d)
+{
+    return a | (b << 2) | (c << 4) | (d << 6);
+}
+
+constexpr u8 swizzle_index(u8 pattern, u8 element)
+{
+    return (pattern & (3 << (element * 2))) >> (element * 2);
+}
+
+enum class Opcode : u8 {
+    Input,
+    Output,
+    Sample2D,
+    Swizzle,
+    Add,
+    Sub,
+    Mul,
+    Div,
+};
+
+struct Instruction final {
+    union Arguments {
+        struct {
+            u16 target_register;
+            u8 input_index;
+        } input;
+        struct {
+            u16 source_register;
+            u8 output_index;
+        } output;
+        struct {
+            u16 target_register;
+            u16 coordinates_register;
+            u8 sampler_index;
+        } sample;
+        struct {
+            u16 target_register;
+            u16 source_register;
+            u8 pattern;
+        } swizzle;
+        struct {
+            u16 target_register;
+            u16 source_register1;
+            u16 source_register2;
+        } binop;
+    } arguments;
+    Opcode operation;
+};
+
+}
diff --git a/Userland/Libraries/LibSoftGPU/Shader.cpp b/Userland/Libraries/LibSoftGPU/Shader.cpp
index 44bb9635eae..ae68fcfd22c 100644
--- a/Userland/Libraries/LibSoftGPU/Shader.cpp
+++ b/Userland/Libraries/LibSoftGPU/Shader.cpp
@@ -8,8 +8,9 @@
 
 namespace SoftGPU {
 
-Shader::Shader(void const* ownership_token)
+Shader::Shader(void const* ownership_token, Vector<Instruction> const& instructions)
     : GPU::Shader(ownership_token)
+    , m_instructions(instructions)
 {
 }
 
diff --git a/Userland/Libraries/LibSoftGPU/Shader.h b/Userland/Libraries/LibSoftGPU/Shader.h
index 7c6b899d05f..e75c094d464 100644
--- a/Userland/Libraries/LibSoftGPU/Shader.h
+++ b/Userland/Libraries/LibSoftGPU/Shader.h
@@ -6,13 +6,20 @@
 
 #pragma once
 
+#include <AK/Vector.h>
 #include <LibGPU/Shader.h>
+#include <LibSoftGPU/ISA.h>
 
 namespace SoftGPU {
 
 class Shader final : public GPU::Shader {
 public:
-    Shader(void const* ownership_token);
+    Shader(void const* ownership_token, Vector<Instruction> const&);
+
+    Vector<Instruction> const& instructions() const { return m_instructions; }
+
+private:
+    Vector<Instruction> m_instructions;
 };
 
 }